Yep. -but -as Brad says- move the output to across the Zener pair. -drop the take-off line down to the other end of the resistor and you're there.
Yes, Zeners are rated in milliwatts (or watts for the big stud-mount type). -The series resistance should be big enough to protect the Zener, but not so big that it divides the voltage (headphone load included) to a wasteful degree... perhaps equal to teh load then you're throwing away 6dB or so...
Then a couple of 400mW Zeners should be fine. -If you're blowing too much power thorugh that then reconsider... but by then you'd have a watt or so into the cans, and by then I know from experience, DT100s are capable of lethal levels!
Funny that DT100's don't see much use over this side of the atlantic: They really are stunningly good headphones, and every single part is available for replacement. -They're a little light on LF, but that works great for backing track applications, where LF bleeds in from around the user, plus the "chest effect" of high-decibel envronments. -AKGs and the like seem to be preferred over here, but they are nowhere near as robust. -If you're blowing DT100's you'd have killed half a dozen sets of AKGs in the same time! :wink:
Keith